Scientific Anglers Mastery Trout GP Fly Line
The casters line!
$79.95
General Purpose Trout Taper. This line is one quarter size heavy and a fly casters dream. They call this “The Casters Fly Line”.
New for 2026, the Scientific Mastery Trout GP Fly Line– General Purpose Trout Taper. This line is one quarter size heavy and a fly casters dream. They call this “The Casters Fly Line”. Available here in the legendary Mastery series.
Fully-featured with a comfortable price tag describes Scientific Anglers Mastery Fly Lines. Mastery Fly Lines offer a number of advanced qualities starting with SA ID for easy line identification. The AST additive provides slickness and durability, while Welded Loops allow easy change of leaders and attachment of backing.
* Mid-length head for exceptional mending and accuracy at distance
* The casters line
* Braided multifilament core
* Utilizing the tapered belly from Infinity, Trout GP has a slightly longer front and rear taper and ¼ size heavy weight scheme. Compared to Infinity, Trout GP leans more finesse but is still a capable general purpose trout line.
* The choice for anglers who don’t consistently fish heavy rigs like large streamers or bulky indicators.
* Available in 3wt- 6wt
* Color is SAGE
Features AST Coating, SA Line ID, Welded Loops
SA Mastery Trout GP 3wt WF-F
* 30′ Head Weight: 110 grains
* Total Head Weight: 155 grains
* Head Length: 47 feet
* Total Length: 90 feet
SA Mastery Trout GP 4wt WF-F
* 30′ Head Weight: 130 grains
* Total Head Weight: 190 grains
* Head Length: 48 feet
* Total Length: 90 feet
SA Mastery Trout GP 5wt WF-F
* 30′ Head Weight: 150 grains
* Total Head Weight: 225 grains
* Head Length: 49 feet
* Total Length: 90 feet
SA Mastery Trout GP 6wt WF-F
* 30′ Head Weight: 175 grains
* Total Head Weight: 265 grains
* Head Length: 50 feet
* Total Length: 90 feet
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Fly line grain-weight specifications
This is the official AFTMA (American Fishing Tackle Manufacturers Association) chart of fly line grain-weight specifications, based on the front 30 feet of a fly line.
Our website lists the grain weights for each line in its description. Compare that weight with the chart to see whether a particular line is true to size or overweighted.
Weight in grains for the front 30 feet of fly line
| Weight in Grains | |||
|---|---|---|---|
| Line Weight | Low | Target | High |
| 1 | 54 | 60 | 66 |
| 2 | 74 | 80 | 86 |
| 3 | 94 | 100 | 106 |
| 4 | 114 | 120 | 126 |
| 5 | 134 | 140 | 146 |
| 6 | 152 | 160 | 168 |
| 7 | 177 | 185 | 193 |
| 8 | 202 | 210 | 218 |
| 9 | 230 | 240 | 250 |
| 10 | 270 | 280 | 290 |
| 11 | 318 | 330 | 342 |
| 12 | 368 | 380 | 392 |
| 13 | 435 | 450 | 465 |
| 14 | 485 | 500 | 515 |
| 15 | 535 | 550 | 565 |
Have more questions? Contact us or watch this video we made explaining the concept:
- Free shipping on orders over $50 within the continental US (UPS Ground or USPS). Orders under $50 ship for $7.95.
- Faster options: 2-Day and Overnight are available at checkout for an additional charge.
- Processing: Orders ship the same day or the next day. You’ll receive a tracking number via email once your package leaves the shop.
- Oversized items: Some large or heavy items carry a shipping charge. If so, it’s listed on the product page and added automatically at checkout.
- Back-orders: No backorders. If we don't have it, you can't buy it!
- International: Canada $29.95 (under 4 lbs) or $49.95 (over 4 lbs). All other countries $49.95 (under 4 lbs) or $69.95 (over 4 lbs).
- Sales tax: Applies only to orders shipped within Ohio.
If you need to return an item for any reason:
- Simply follow the instructions that are provided with each order.
- Send us a quick e-mail, [email protected] and / or drop a note in the return package with the following information: Your name, Order Number, Item(s) and a quick note on reason for returning.
These instructions will also be printed on the return/address form. Please note that if it has been longer than 30 days, we will need to contact you to get a credit card number in order to apply for the credit. Please make sure that we get a good phone number in that case. - Drop the item in the Mail / UPS to us and that’s it – We’ll be looking for it!
We will be waiting for the item and will issue an immediate credit to your credit card account or you may leave the money on the store account for future purchases. If we don’t hear otherwise, the refund will go back on the exact card used for the transaction. *Note: If an item was not purchased via the internet, phone or the purchase was made more than 30 days previous, we will need to contact you to secure a means of credit.
- Once we process your return, we will make a note on your “Customer Service Notes” and then drop your return/credit receipt in the mail.
- Non-defective, returned merchandise must be in re-sellable condition.
- Please make non-defective returns within 30 days of purchase – please contact us if more time has passed.
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